Browsing by Author "Chandramali, EAG"

Now showing 1 - 6 of 6

item: Conference-Extended-Abstract
Develop an efficient GIS embedded web application to manage the field data -a case study of damage assessment in lands combining maps and,GPS measurements
(2014-01-16) Chandramali, EAG; Wijesekera, NTS
In the present day web applications, location based interactive requirements are increasing. WebGIS applications are moving towards applications that have many user levels incorporating data entry, verification and decision making. Coordinates of a location are the most important data for such applications. Boundary determination, decision making, area calculation, distance measurement, comparison of land parcels etc, are some of the functions that need to be done for land management and assessment process. Way points collected from Global positioning System (GPS) units should be converted to information that can be analyzed for land management. A reliable, efficient and accurate GIS embedded Web application was designed by using crop damage assessment as a case study. HTML, Javascript and PHP were used for the development. Web Component, GIS Component and Database Component are the three main components of the application. Accuracy of data were verified by using four methods. The developed damage assessment tool was designed to store and process field data related to crop damage and to visualize map information to evaluate a crop damage. Incorporation of layers include both raster and vector data. Main functions of the applications are I. Upload coordinates and relevant photographs II. Convert polygons into polygons III. Browse for maps and photographs IV. Visual and value comparison of polygons of pre and post damage extent. Higher accuracy level of locating, efficiency and accuracy of data entering through direct capture, remote access facilities, and easy to use functions are the benefits of using this application.
item: Thesis-Abstract
Development of multiple query web GIS for growing databases : a case study of land and water information management
Chandramali, EAG; Wijesekera, NTS
Land and water information systems are developed for managing the information such as location, its limit , characteristic, structure, ownership if available and other relative attributes. For presenting the geographical locations of the land and water features, map based systems are being developed. Present day Geographic Information Systems (GIS) are map based systems which enable the interaction of several map layers for desired output. Most of the available WebGIS applications for land and water information are limited to selected features, such as roads, rivers, buildings and forest features. Some are limited to defined Geographical area, while only primary attribute values are displayed by some other applications. However, with the increment of requirements for WebGIS application, information and functions are being enhanced rapidly. When serving large data through a WebGIS application, performance tend to be slowed. Therefore it is important to identify the issues of WebGIS application in case of growing databases. Overall objective of the study is to identify the issues and concerns related to the development of Web GIS applications for growing databases and then to develop a land and water information system in order to identify management issues pertaining to the tool development associated with map serving and combined querying. The specific objectives of the research are: Identification of WebGIS performance issues with respect to the spatial coverage expansion and attribute expansion and development of a land and water management WebGIS tool with user friendly search capability considering possible expansion of coverage. As very first step, the issues of available web GIS applications are identified by a literature survey. Meanwhile, a evaluation on development methodology, performance optimization techniques and performance calculation methods is carried out. The work commenced with the development ofWebGIS application including information and functionality at basic level. According to the user survey, the application was enhanced for another three stages with growth of database and functional operations. The growth rate of database size second stage of the application is twice than first stage. While third stage growth rate is five times than second stage and fourth stage having about fifteen times of growth rate of features. The testing process of each stage was carried out to identify user familiarity, accuracy and performance level of the application. Performance level was identified by calculating the response time of functions at each stage. GeoInfo WebGIS application with better efficiency level of functionalities, user friendly features and high accuracy level is one of major results of this research. Functionalities ofWebGIS application are listed as (i) Query for land and water features, their attributes and relative features. (ii) Map the geographically location of water and land features and (iii) GIS operations such as location identification, measure length/area, map zoom in/out, pan map and vector and raster data layers loading. JavaScript, XML, HTML, and PHP are programming languages for the development of the application, while Postgis is selected as the database.Database to database functions take high response time of 22.5 seconds in Version 4 while map to database ii having the 3.42 seconds as minimum compared with first level ofWebGIS function categories. When considering all the functions are considered, ”Measure Tool Operation” has the minimum response time of 0.42 seconds and Maximum is the 59.2 seconds and it is the response time of ”Displaying list of Buildings” function. A rapid increment of response time is with functions of fourth versions. Other identified issues are non responsive situations with loading images, take more time to data loading and map overlaying when browsing and changing . By evaluating results of the verification process it is identified that database transactions directly affect the efficiency of functions ofWebGIS application. Reasons for Identified issues of WebGIS land and water management are (1). Issues with performance of stored procedure (2). No factor query index (3). Low efficient configuration of server (4).Issues with cache memory and (5). Trying to load heavy maps and data Recommendations for WebGIS development are (1).Database to database functions should be minimize as possible for the best performance of Water and land information management WebGIS application. (2). When serving the Raster and Polygon data, size should be in small components as possible. (3).Careful action should be taken when loading more than 10 or 20 records at a given time
item: Article-Abstract
Evaluation and selection of tools for data migration from non-spatial to spatially referenced software : a case study migration from MySQL to PostgreSQL
Chandramali, EAG; Wijesekera, NTS
Geographic Information Systems and open source software are becoming more and more popular resulting in an increased requirement for data migration from common non spatial software to spatially referenced software. MySQL is a very popular open source Database Management System used by most web developers but without support for spatial referencing. PostgreSQL is an open source software that supports Geographic Information Systems. It is often necessary to migrate data from MySQL to PostgreSQL and it is possible to identify many tools that are capable of executing the desired task. Therefore best available tool should be selected to ensure that the selected tool satisfies the main functionalities expected of the software and capabilities of performing the tasks with user friendly features. This paper describes a systematic methodology adopted to select the best free tool for data migration from MySQL to PostgreSQL using literature and rational judgement incorporating a qualitative ranking system to Migrate the base data. For easy comparison, an Evaluation Score of Tool was defined by calculating the percentage of available functionality when compared with the user desires for satisfaction. After comparing three available tools, Postgres Plus 8.3 free software was identified as the best with a Evaluation Score of Tool value of 76%. The present work identified 3 main and 11 sub database functions together with 4 main and 13 sub components of Graphical User Interface functionality as important parameters for data migration.
item: Article-Abstract
Field Data Collection for Land Information Systems – A Case Study on Quantification of Resource Requirement for a GIS
Chandramali, EAG; Wijesekera, NTS
Field data collection is the most important component for application development. Field data significantly affect the results of a research or a project. Therefore it would consume a substantial period of time unless field data collection is suitably designed, properly planned and executed with minimum gap fill data collection efforts. It is important for field data collection programs to carefully ascertain the required data, accuracy requirements and incorporate suitable verification tools. In order to achieve success of this process it is necessary to have a well organised methodology to evaluate available methods and tools for data collection, gap filling, verification and evaluation. This must be achieved through a good literature review, and then selecting and creating suitable methods, requirements and resources for data collection. The study area is around university of Moratuwa in Moratuwa DSD of Sri Lanka. It is a semi urban area of approximately 2.5km2 with nearly 6000 buildings and 300 roads. The area was divided into ten zones for data collection purpose. Georeferenced Google images, a pre tested data collection sheet, printed maps, Magellan Triton Handheld GPS and 38 data collectors were the resources used for the data collection process to capture spatial data. Total number of buildings collected from the survey is 5175 which covered the 17.97% of the extent. 469 Roads with a total length of 52,920m and classified into six road types covered 5.99% of the total area. The data capturing rate was approximately 5.5ha of land area and 3.8% of building units per averaged person per day. To capture these data, collectors traveled 162.5km within the data collection area consuming 102 person days. This research provides a systematic approach and guideline quantification supporting GIS planners to prepare project estimations.
item: Conference-Full-text
Identification of WebGIS Development Potential and Issues – A land and Water case Study Application for Moratuwa, Sri lanka
(2014-05-07) Chandramali, EAG; Wijesekera, NTS
Popularity of internet use is rapidly increasing. Hence, the demand is high for Web based GIS tools. The need to handle heavy maps and attribute datasets, often increase issues especially with respect to the time taken to serve maps and to filter user desired information for delivery. A WebGIS based land and water information management system was developed for a land extent of approximately 2.5km2 within the Moratuwa DSD of Sri Lanka. Information of roads, buildings were collected as land data while water and stream information were collected using an extensive field survey. The developed WebGIS application integrates digital base maps and feature attribute data of the selected case study area and facilitates operations through a user-interface while offering a variety of querying and reporting options. This application which was named GeoInfo WebGIS, possesses a very high potential to serve the users through i)Map to Map ii) Map to database iii) Database to Map and iv) Database to Database functions. The application was tested and verified through a consideration of user satisfaction and accuracy. GeoInfo WebGIS was developed on MS4W framework, PostgreSQL was used as the database. Non-responsive situations, high time consumption when loading the data layers, map overlaying issues and delay in refreshing the maps are performance issues identified through the application development.
item: Conference-Full-text
Identification of WebGIS development potential and issues - a land and water case study application for Moratuwa, SrI Lanka.
(Department of Civil Engineering, University of Moratuwa, 2012-12) Chandramali, EAG; Wijesekera, NTS; Nawagamuwa, U; de Silva, LIN
Polularity of internet usuing is rapidly incerasing. Hence the demand is high for Web based GIS tools. The need to handle heavy maps and attribute datasets, often increase issues specially with aspect to the time taken to serve maps and to filter user desired information for e very. A WebGIS based land and water information management system was developed for a land extent of approximately 2.5km’- within the Moratuwa DSD of Sri Lanka. Information of roads, buildings were collected as land data while water and stream information were collected using an extensive field survey. The developed WebGIS application integrates digital base maps and feature attribute data of the selected case study area and facilitates operations through a user-interface while offering a variety of querying and reporting options. This application which was named Geoinfo WebGIS, possesses a very high potential to serve the users through i)Map to Map ii) Map to database iii) Database to Map and iv) Database to Database functions. The application was tested and verified through a consideration of user satisfaction and accuracy. Geolnfo WebGIS was developed on MS4W framework, PostgreSQL was used as the database. Non-responsive situations, high time consumption when loading the data layers, map overlaying issues and delay in refreshing the performance issues identified through the application development.